Hyperfrequency electron tube



Sept. 9, y1952 E. ToURAToN E-rAl.

HYPERFREQUENCY ELECTRON TUBE Filed Oct.

QN mw A Homey Patented Sept. 9, A1952 gfipplieatimioemher 1, 194s; serialbzw-52,233 U "..zgrfFi-anee oetobjerhanlw "fThe v,piesent inyenton lelatesf 'to vacuum 11i-bes operating' jat Very highj frequencies v and` more particularlyto yacuumtubesof this'typ'e in-'whicl-i an' electron beam flows thiou'ghf"one-orr seyeal bi1-cuits 'through'lwhich afprogre'ssive'fwaveflows.

amplifiers n One object of the pijesenfs-"inveil-tion-frelatesT to the manufacture of afvacuum tubeinwhich the 'densityjof the el'ec'tron' beam fis' f; high-*so A'as-*to 'increase the high; frequency' output-"of the-t be.

'Suchtubes 'areusedj'fin particular-asfwideband V-Another 'object*ofthe-"present"inventionis :to

`je1irninatey the ionsl produced by the' lectron beam `insidey the vacuun'` tu'lle-` and tofidthe tubef -of one 'cause of' naifasitic- "oscillations-^tvhich-occur frequentlyin-tubesof-this'kil'.

According fto'f'onefeature 'of' the"invention-l a Hollow tubular' electron'beamis made to'f-foW-in the Vvicinityv of a?lielicoidallyv woun 'ribbon'. The useful high fequency'eldis''the-discontinubus held-prevailing between the-successive tuns of the helix. LTThe relativelyk large ldiameter- -bf' this helix' nia-kes@ it lpossible'tofotiemte the" tube with 'a vhollow tu'bularqelctronfbeam -Witli'-l a'"fl`farg'e cross section, a highintensity"andflowdensity, which `areV favourable conditions for? th-bunchilngfoff'the'elfect'rons. 1

f-Aecor'ding to'anothe1-fature ofthinvention th-length 'ofievery turn isequal-toone half-bf waveie fgthsofthe .wave t- 'be amphi-eed..

Hceoidingl to another" :featureY of' theinveriti'on af-rrietal` rodA 'Wlith"the' s'ameiaxisl -as'i the helix islprovided inside the helix'. l Thisfrod can provide aicertai'namount:of-"attennation-'sovas1 to; prevent lime/propagationfof-high jfrequencyfcurrentsl.

Accordingtoanother 'ieature'bf the rfi-mention YthisInetJaI--:rod is 'broughtto a poten-tia different from the potential! of! the helix, thus establishilngfv iradialf felectricalelfd' between the frodand the! lix( f ifzlicccivding"1'toa-otheri 'feature "of-fthe invention uthe,"'ele'ci'a'zon beam is subjected 'at the- :same time tof a uniformlongitudinal ymagnetic-'-field and to a:radialfelctricalzel. f Itli's-'lthus-possible to- 'var-'yf the f mean-f Lradius of the; beam-lf andiL its thickness-'by Vaif'ying- -the'f intensi-ties of l them-agnetc-andltheelectricalields;

vven'tion; and*v nul or slightly negative potential.

achim. (on sis-(39) utrice-I heid set-up between the-fmeta1-r0d-andt1fe helix 'is 'useful for' getting"r'i'djofY theV ions; which are collected .jeitherby"'the'11od or vthe helix according to whethertheiadial electrical eld'is directed towardsthe rod or the helix'.

The above and other features andobj'ects. of

Zthisin'vention' Aand the manner( -of `attainirg'jthem will "become more' "apparent "and"H the invention :itself Kwill -be "best understood by reference to fthe following description" of` `'an' 4enfibodiment' of `4the invention taken- .inf-commence with- '-th eae'- companying' `jdijawinygs fwherefin: Y

Fig. -1 shows schematica-uy a, ieres'srsgecton-ef'g- Fig;- 2 shows a cross section-y voi?I a-specic einb'oiii ment of thevnventioni Fig. 1 shows an annuiai'jcatlodepiovied with an electron emissive'coatin'g heated ,byai-Iamem j(not shown) .A Y'.Uhe" potential 'of "the rcatl'ioe` will -be -considered` as potential-zero jforfthe` rest" fof the description. 'I'l'ieele'ctrons emitted byr the tubular-beam 2TV by means 'of anelec'tiode Sat-"a A"longitu'd-i'nalA magnetic l'is producdibyf a coil- 4 coaxial"- lwith 'the tube; the magnetic- 'eli 'may be ladjusted byva-ryingthe current"applied to the-.coil vby means 'of an-ext'e'rioifsoinifcev fof supply-(not shown)v The electronfgun is 'subjected as` awhole tothe magnetic eld lset pbythe een. zinueftc 'the action offthis magnetieffem the electrons of the' beamV` rotate` about'- `a'ixi-sf 5 of. the tube A' l A FfolloW-ingthe' electron-gun,l -is'z-prov'itfed an electrode 6; whichfisshownschematicallyfon 'the drawing as afcyI-indrical-tube coaxial WithfaX-is ofthef-tube. electrode -is broughtA high potential. AsaV niatteif" `vof aGtfTtS- 'le'e' 'trede 'constitutes the-circuit oifcircu-t'sz through which the progressive-waves fow and may? take the:- 'form-bf' any-'appropriate structure-Used? with such tubes.

ff Anon-'1er'electrode4 11 loca-ted 'inside-and-coaiiially thel tubular electrodeandi iWi-ththe same axis s brought 'to a Vh igh-pot'er-iti'al" different-from ythat appl-edbto electrode@ -'Thisf-electifode ab tendsbeyonri electrode; 61 -as-faiif asitliee'side of 'aolecoff'electrbdb which! collects' lie-*lectron beam. This collector electrode; may loe-:brought 3 to a higher potential than that applied to electrode 6 and may be located outside the magnetic field set up by the coil 4. The path of the electron beam through the various electrodes is shown on Fig. 1 starting in 9 near cathode I and terminating in I on the collector electrode 8.

The adjustment of the intensity of the longitudinal magnetic eld and that of the radialelectrical eld make it possible to vary, within certain limits, the mean diameter and the thickness of the tubular electron beam I I at the level of the oscillating circuit. The longitudinal eld of the electrons which'is low when the electrons leave the electron gun in 9 increases in the interl5 val separating the electron gun from electrodes Sand'l.

v, size y, the connections between the ,output leads s vIll'and the electrodesy have not'ib'een shown for Line 6 is matched at bothvends by means which n have not been shown, but whichmay be con-` structures well known in the art.

Fig. 2 shows a specic embodiment of the vacuum tube represented schematically on Fig.

1. The tubular cathode -beam is generated by` the sake ofclarity. While wave guides 28 and 2 9 are used for the input and output connections,

'it is clear that other means known in the art `may be used'instead. Rod 34 is maintained inside the collector electrode 3I by an insulating i riiig`44. stituted for example by wave'guidesvor coaxial an electron gun I2 comprising for instance; aj,

cathode I3 of annular shape at the end I4 of which isv deposited an electron emissive coating, a ,concentrating electrode comprising members I5, VI6 and I'I.Y Member II is screwed inside element I6 and holds the cathode I3 by means of a mica disc I8 on which the said cathode is mounted. Y

Member I6 is screwedinto member I5 which is held in placebythree insulating rods I9 at 120 one from the other. The assembly of the electron gu'nvis maintained in theglass envelope 20 by a conventional resilient arrangement (not shown).

A cylindrical electrode 2| following the electron gun is held by aninsulating rod22 extending insidemembers I6 and Il-" The three rods I9 hold in place at one of their ends'another tubular electrode 23 on whichrepose three insulating rods 24 at 120 one from the otherl (only one of these rods is shown on the. drawing) in order to avoid confusing the drawings.

The helically wound ribbonv 25 is held on place inside the tube, by the three 4insulating-rods 24. This helix is provided at both ends with radiating antennae 26 and 2'1 which, with -the input and output-Wave guides 28 and 29, terminate it with the appropriate impedances. antenna 26 is connected to electrode 23and the endk lead of antenna 21 toV electrodeSEJ similar to-electrode 23. Electrodes 23 and `iilare thus brought to the same potential as ribbon 25.

The collector arrangement comprises` a collector lan insulating member 36 and the other end of the central electrode is held in place by means of an insulating member 3T which is xed. to electrode 2I. provided Ywhich tends toL push electrodes 34 and 32 one against the other. This resilient arrangement is not visible on the gures and may be constituted for instance by a spring inside member I6.

The electrical connectionof electrodes 2l and 34 with the central electrode 35 is made bymeans of small size conductors 38 and 39 wound in the shape of a spring Which-may be provided with a coating in order to present an increased attenuation. This connection, is shown by wayv of .example, but itis possible to use otherponnecting The end lead of A resilient arrangement can be Y In the arrangement shown in Fig. 2 an electromagnetic wave `travels along the helix. There is no appreciable axial electrical component, and,

' therefore, it is possible to introduce axial elec-` trode v35"without disturbing the electrical field inside the tube. On the other hand a D. C. radial electrical field, between the central electrode and the helix, makes it possible to collect the electrons in this region of the tube and. therefore to suppress one cause of parasiticY oscilla.- tions. This radial electrical `field repulses the ions towards 4one orthe other electrode according tothe direction of the electrical field; the elimination of these ions improve the operative stability ofthe-tube.. y

The distance between two consecutive turns of the helix is chosen inv suchra way that. the time, taken by the electrons to flow over this distance, be equal to` one `halfperiod of theapplied high frequency Wave. Thus theV same electronsare always subjected to the same high frequency eld in the diierent intervals.' The ratio of the longitudinal eld to thetangential speed of the electrons is suchVI that the electrons yflow substantially perpendicularly through the Vintervals of the helix. The ribbon can be uniformly attenuated along the helix or at given points.

While we have disclosed particular apparatus for carrying out our invention, it should be understood that such-apparatus is submitted as illustrative of the invention only andrnot as a limitation on the scope thereof.

l. A travelling wave vacuumtube comprising in combination means for generating a hollow tubular electron beam for ilow along a given path, an helically wound conductor surrounding and coaxial with said beam path, a cylindrical metal electrode inside of and coaxial with said beam path, means for applying a longitudinal magnetic neld axially of said beam path substantiallyv co-extensivey with the lengthY of said helically wound conductor and means electrically connected to said conductor and said electrode to applythereto a difference of D. C. potential.

2. A travelling wave amplier tubecomprising an electron gun for .generating an annular beam of electrons, a collector forv said electronsjspaced from said gun to denne a beam path therebetween, a wave input-.connection proximate said gun and a kwave output connection proximate said collector, wave velocity lretardation means connected between said. input connectionand said output connection, acylindrical-metal electrode posltioned'coaxially and centrallyroff said beam path, means for creating a magnetic eld length: w1seoi1said beam path substantially co-extensve with the Space between said wave input connection and said wave output connection, and means for applying potential to said electrode whereby said potential and said eld cooperate to remove ions from said beam path, said retardation means comprising a helcally wound conductor spaced concentrically of said cylindrical electrode and outside said path.

EMIL'E TOURATON.

RENE ZWOBADA.

REFERENCES CITED The following references are of record in the le of this patent:

6 UNITED STATES PATENTS Number Name Y Date 2,064,469 Haef Dec. 15, 1936 2,181,850 Nieou Nov. 2a, 1939 5 2,300,052 Lindenmad @027.1942 2,541,843 Tiiey Feb. 13, 1951 u .LT-IER REFERENCES Article by Pierce and Field, Proc. I. R. E. for 10 February 1947, pgs. 108-111. 

